The castle was originated from a fortified building was erected in the 13th century next to the city's walls. This first building was called Castelvecchio ("Old Castle"), and was the seat of the Bishopric of Trent from the 13th century onwards to the end of the 18th century. The castle is composed of a series of buildings of different eras, enclosed by a circle of walls in a slightly elevated position above the town.The, as called, Castelvecchio is the oldest and most dominant building of the entire housing development. The Magno Palazzo is the sixteenth expansion in the forms of the Italian Renaissance, wanted by the Prince Bishop and Cardinal Bernardo Clesio (1485-1539), the third part, in the southern end of the complex is the known Eagle tower, which preserves the famous Cycle of the Months, one of the most fascinating pictorial cycles of profane the late Middle Ages.[1]

Bishop George of Liechtenstein was the first to enlarge the castle, in the late 14th century, turning it into a well-styled residence. The Castelvecchio was further modified by Johannes Hinderbach, who had the double loggiato and the Gothic entrance gate built. In the first decades of the 16th century, Bishop Bernardo Clesio had a new residence, called Palazzo Magno ("Grand Palace") built in Renaissance style alongside the old castle. The last great addition was the so-called Giunta Albertiana, from the name of Bishop Francesco Alberti Poja (1686), with which the Castelvecchio and the Palazzo Magno were united

The castle remained the seat of the Prince-Bishops until 1803. Used by the Austrians as military barracks and, later, as a jail, it decayed. In the 1920s, when Trento was returned to Italy, it became seat of a National Museum and was restored. Since 1992 it is home to the Provincial Gallery of Art.

Frescoes in the Torre Aquila: January.

According the legend, it was connected by a secret tunnel to the city's cathedral, which allowed the prince-bishops to move unseen between them.[2]

The interior halls have precious frescoes, including those in the Torre Aquila ("Eagle Tower"), which are one of the most noteworthy examples of International Gothic art in Europe: they represent the "Cycle of the Months" (15th century) and were made by an unknown artist from Bohemia. The cycle is interesting also for its accurate portrayal of the landscape, the economic activities, the habits and the fashion of Medieval Trentino. The walls of Torre del Falco (late 16th century) have frescoes with hunting scenes, also a rare example of German landscape painting in northern Italy.

Romanino's frescoes in the Loggia del Cortile dei Leoni.

The Palazzo Magno (Big Palace) section was decorated in the early 16th century by order of prince-bishop Bernardo Clesio. Dosso Dossi and his brother Battista were entrusted the decoration of the Sala Grande, Sala degli Specchi, the Camera del Camin Nero, the Stua della Farnea (the refectory), the Library and others. Girolamo Romanino frescoed, among the others, the loggia in the Lions' Court (Cortile dei Leoni) with typical Renaissance themes, such as mythological or ancient Roman episodes, as well as biblical ones, and others from daily life. He also painted a portrait of Bernardo Clesio in the Sala delle Udienze ("Audience Hall"), accompanied by those of members of the Habsburg family (for which Clesio had worked as a diplomat).